A conventional loading dock for transport vehicles typically has a dock leveler with a dock bumper placed on each side of the lip at a fixed position on the dock face. The width of the dock leveler is usually limited to a maximum width of seven feet because if the bumpers are placed wider apart then there is a risk that the vehicle may miss the bumper and strike the dock leveler when it backs into position. Some specialty dock levelers are wider than seven feet to provide space for wider than normal cargo. Examples of these devices are shown in U.S. Pat. Nos. 5,881,414 and 6,070,203. A dock leveler with the bumpers mounted rigidly on the front as described in U.S. Pat. No. 6,070,203 may be unable to raise and extend the lip. A transport vehicle may be positioned against the bumpers with sufficient force to prevent the dock leveler from raising, or the top of the bumpers may strike a door hinge or other protrusion beyond the rear of the transport vehicle. By retracting the bumpers there is no interference to raising the dock. The bumper mounting shown in U.S. Pat. No. 6,070,203 could potentially have utility with the lip that extends linearly such as shown in U.S. Pat. No. 6,081,954. The hypothetical reason is that since the lip does not rotate down in front of the leveler there is no requirement for the lip and the bumpers to occupy the same space. However if the bumpers cannot be retracted they may interfere with the transport vehicle and prevent the leveler from raising to extend the lip. Consequently such a theoretical structure still has significant shortcomings.
U.S. Pat. No. 4,420,849 shows a dock leveler with bumpers that fold away to accommodate wide loads, but with all of these devices the width of lip is limited by the space between the dock bumpers.
U.S. Pat. No. 6,081,954 describes a dock leveler with a lip that extends linearly rather than rotating in the conventional manner. However the distance between the bumpers would still limit the width of the leveler.